The most famous exoplanet hunter to date, NASA’s Kepler space telescope detects the dips in starlight as newfound planets pass in front of their stars.

Set to launch in 2017, Cheops will look for such transits in a more focused, paparazzi fashion. While Kepler uses a wide-angle crowd shot to scan several systems, Cheops will home in on one star system at a time in search of the most interesting planets.

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From estimates of mass and radius, Cheops will calculate the density of these planets and thus infer their internal structure, including whether they are rocky. It will also use transits to tell if a planet has an atmosphere.

Top of the A-list right now is the newfound Alpha Centauri Bb, the closest known exoplanet to Earth, says Cheops coordinator Willy Benz at the University of Bern, Switzerland.